Using GDI+ to make 'PNG with added CMYK' ?

Question

I want to create a PNG file from a System.Drawing.Bitmap with the colours defined using CMYK.

I can create the PNG OK but how do I define 'with CMYK' ?

I've looked at the encoderparameters argument to the save method but it seems to me they don't cover what I need ?

Any pointers/samples appreciated.

thanks

Answer 1

The PNG format was designed for transferring graphics for display on computer screens. PNG files may only transfer grayscale or RGB/RGBA image data; you can't have a CMYK PNG file: http://www.w3.org/TR/2003/REC-PNG-20031110/#11IHDR

Answer 2

Oh OK I was unaware of that. The file is only to embed in a PDF so maybe I could make the question more general - how would you ask a System.Drawing.Bitmap to save to any format 'with CMYK'